Android异步任务在后台执行错误

Question

我试图创建一个连接到本地主机上的数据库的活动，在用户填写表单后，表单在后台方法中使用asyntask.do提交给本地主机。我得到一个错误，我不太确定什么是错误的，请我需要帮助。

这是我的logcat

`01-30 06:03:10.451: E/AndroidRuntime(1332): FATAL EXCEPTION: AsyncTask #1 
    01-30 06:03:10.451: E/AndroidRuntime(1332): java.lang.RuntimeException: An error occured while executing doInBackground() 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at android.os.AsyncTask$3.done(AsyncTask.java:278) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.FutureTask.run(FutureTask.java:137) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.lang.Thread.run(Thread.java:856) 
01-30 06:03:10.451: E/AndroidRuntime(1332): Caused by: java.lang.NullPointerException 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at com.oose.buddiev2.RegisterActivity$CreateNewUser.doInBackground(RegisterActivity.java:101) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at com.oose.buddiev2.RegisterActivity$CreateNewUser.doInBackground(RegisterActivity.java:1) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at android.os.AsyncTask$2.call(AsyncTask.java:264) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305) 
01-30 06:03:10.451: E/AndroidRuntime(1332):  ... 5 more` 

这是在活动

class CreateNewUser extends AsyncTask<String, String, String> { 

    /** 
    * Before starting background thread Show Progress Dialog 
    * */ 
    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     pDialog = new ProgressDialog(RegisterActivity.this); 
     pDialog.setMessage("Creating User.."); 
     pDialog.setIndeterminate(false); 
     pDialog.setCancelable(true); 
     pDialog.show(); 
    } 

    /** 
    * Creating User 
    * */ 
    protected String doInBackground(String... args) { 

     String usernameString = usernameEditText.getText().toString(); 
     String emailString = emailEditText.getText().toString(); 
     String passwordString = passwordEditText.getText().toString(); 

     // Building Parameters 
     List<NameValuePair> params = new ArrayList<NameValuePair>(); 
     params.add(new BasicNameValuePair("username", usernameString)); 
     params.add(new BasicNameValuePair("email", emailString)); 
     params.add(new BasicNameValuePair("password", passwordString)); 

     // getting JSON Object 
     // Note that create product url accepts POST method 
     JSONObject json = jsonParser.makeHttpRequest(url_create_user, 
       "POST", params); 

     // check logcat for response 
     Log.d("Create Response", json.toString()); 

     // check for success tag 
     try { 
      int success = json.getInt(TAG_SUCCESS); 
      // int success = 1; 

      if (success == 1) { 
       // successfully created product 
       Intent i = new Intent(getApplicationContext(), 
         LoginActivity.class); 
       startActivity(i); 

       // closing this screen 
       finish(); 
      } else { 
       // failed to create product 
      } 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 

     return null; 
    } 

    /** 
    * After completing background task Dismiss the progress dialog 
    * **/ 
    protected void onPostExecute(String file_url) { 
     // dismiss the dialog once done 
     pDialog.dismiss(); 
    } 

Answer 1

我的异步任务不能在doInBackground做到这一点。

尝试通过从doInBackground删除，或者你可以把这个OnPostExecute（）：

startActivity(i); 
finish();